Arch heating system for electrical apparatus



J. LELONG Nov. 22, 1949v v ARCH HEATING SYSTEM FOR ELECTRICAL APPARATUS Filed July 12, 1946 Figi Patented Nov. 22, 1949 ARCH HEATING SYSTEM FOR ELECTRICAL APPARATUS Jean Lelong, Claye Souilly, France, assignor to Procedes Sauter, Paris, France, a corporation of France ApplicationJuly 12, 1946, Serial No. 683,109 In France July 13, 1945 3 Claims.

The present invention relates to the heating of the arch in furnaces, roasting apparatus, stoves and other bodies heated by electricity, more particularly domestic heating apparatus as well as electric cookers.

In such apparatus, the heating of the arch is generally effected by means of radiating resistances, that is to say, either bare resistances mostly exposed, or covered resistances, enclosed and glowing. These resistances are disposed in more or less sinuous paths joined to the terminal connections. The heating unit is usually detachable and suspended under the upper wall of the furnace.

In case of a local fault in the heating elements of the furnace, it is necessary to repair or replace the whole heating body. Moreover, the known constructions have the disadvantage of reducing considerably the useful free height of the furnaces.

The present invention has for its object to remedy these various disadvantages. The subject of the present invention is a system of radiant arch heating for electric apparatus such as furnaces, grills, and so on, constituted by a series of individual heating elements separately mounted and individually separately energized and at least partly enclosed in the upper part of the furnace.

According to the present invention, the radiating elements may be of any type whatever: enclosed or with exposed resistances, for example, and may be of any Shape but preferably rectangular. The most advantageous arrangement, to which the invention is not limited, consists in using straight and parallel elements extending in the direction of the length of the furnace.

The number of these radiating elements may be varied, the distance between two consecutive elements being so selected as to afford a good distribution of heat in directions perpendicular to the axis of the elements. This result will be obtained when the distance between consecutive elements is such that the zones of radiation overlap one another to a sufficient extent in a plane parallel to the arch of the furnace and located at the minimum distance for practical use. This result can be obtained in practice only with two, three or four straight elements in a furnace of dimensions as now generally employed.

The accompanying drawing shows an example of construction of a heating system according to the present invention applied to the arch or roof of a domestic heating oven as well as several accessory arrangements of the invention, wherein:

Fig. 1 is a perspective vertical view seen from the front of the arch and wall of the oven assumed to be open.

Fig. 2 shows in longitudinal section a method of mounting a heating element in the oven arch or roof.

Figs. 3 and 4 show diagrammatically the possibility of using at volts or at 220 volts an apparatus iitted according to the present invention with an even number of heating elements.

As shown in Fig. 1, the rear Wall of the oven is indicated by l, the arch or roof by 3, and the hearth by 2. The heating body is constituted by three bars or elements 4 and there can be used advantageously, in this case, for each of these bars, an electric radiant heating element consisting of resistances located in the interior of recesses formed in an insulating refractory lining situated in a metal casing, the refractory lining being formed of a series of abutting detachable plates, the assembly of the plates being held in the casing by an insulating member 5 iixed on the latter and carrying the two terminal connections of the resistance such as described in the specification of my copending application Ser. No. 683,110, led July 12, 1946.

An advantage of this heating system is to ensure a distribution of the heat, theoretically uniformly, in directions parallel to the axis of the radiant bars. The bars, located within the oven, may advantageously be enclosed partly or wholly in the recesses provided for this purpose in the upper part or roof of the oven and, for example, stamped out in the case of a sheet metal construction.

As has been stated above, there results from the system according to the present invention, an appreciable gain in the useful height of the furnace which is free from all obstructions, and an increase in the heat output of the oven compared with other heating systems.

The mounting of the bars in the oven can be effected in any way. Advantageously, in the case of bars to be mounted or removed through the back of the oven, the following arrangement can be employed for example, represented in Fig. 2 and capable of being used according to the arrangement disclosed in my aforesaid application.

At the rear of the oven, the bar 4 abuts against the sides of the opening by which it passes through the back wall I. At the iront of the oven, the bar 4 has a small tongue 6 of spring metal which engages a projection or prong 1 provided for this purpose. The bar is thus both supported and held by friction of the tongue on the projection.

Another important advantage of the present invention is the possibility of easily using different electric connections of the bars and of being able to use apparatus tted with an even number of elements for 110 volts and 220 volts, by a simple changing of the connections.

If there is considered, by Way of example, an oven fitted with four straight bars, constructed for use with 110 volts, the furnace may be supplied either with 110 volts by parallel connecu tion, as shown in Fig. 3, or, with 220 volts by a series-parallel connection, as shown in Fig. 4.

Iclaim:

1. In a radiant arch electrical furnace, a plurality of individual straight heating elements, a furnace structure having a front Wall and a back wall, and an arch, said arch being provided on the inner face thereof with individual spaced recesses extendingr longitudinally of said furnace between said back and front Walls thereof, and adapted to receive said straight heating elements, said back Wall being provided with individual openings in register with said recesses in said arch and through which said straight heating elements are slidingly received, supporting means carried by said front wall for detachably supporting each said straight heating element, an electrically insulating block member attached to each said heating element exteriorly of said back Wall and in abutting relation with said back Wall supporting said heating element thereagainst, and individual terminals for each said straight heating element mounted exteriorly of the wall of said furnace on a said insulating block member.

2. A furnace according to claim l, said supporting means being a projecting prong member carried by said front Wall and each said heating element carrying a spring tongue engageable with said prong member.

3. A furnace according to claim 1, said furnace structure being constituted of sheet metal, and said recesses being stamped in the sheet metal constituting the arch of said furnace structure.

JEAN LELONG.

REFERENCES CITED The following references are of record in the iile o this patent:

UNITED STATES PATENTS Number Name Date 996,454 Carpenter June 27, 1911 1,456,878 Kohn May 29, 1923 1,472,139 Reid Oct. 30, 1923 1,889,362 Hogel Nov. 29, 1932 2,020,127 Stansel Nov. 5, 1935 

